Swimmer's Itch Study Completed

The study conducted by Dr. Raffel from Oakland University is complete. Dr. Raffel's summary is below.​First, thanks to those of you who took time to attend my public presentations this past weekend, and who asked such insightful questions. I am continually amazed and gratified by the amount of public interest and enthusiasm about this project.

Second, please find attached the revised (final) report about our work and findings. In my opinion, the most interesting results were the following:

Stagnicola snails were associated with deeper lakes and sites with more deciduous (shade) trees). Both patterns could plausibly be caused by a preference for colder water temperatures in this group of snails, which is mostly found at northern latitudes.

There was a very strong negative association between submerged vegetation and cercaria levels, which seems to be a real biological pattern (i.e., not driven by statistical outliers or spurious correlations with other predictors). This might be caused by vegetation blocking cercaria moving in from off-site, or the presence of beneficial plants like Bladderwort that can remove cercariae from the water.

We found support for our our hypothesized effect of water clarity on snail abundance. However, I later realized that this pattern was driven almost entirely by non-host snails (pleurocerids) and was therefore irrelevant to the swimmer's itch story. Pleurocerids dominated the snail community at most sites.

I think the key findings are likely publishable in a field-specific journal like J. Parasitology, at least once we have done some additional follow-up statistics to make sure we've covered all our bases. This might take us a little while, since I have several other high-priority papers to try to get out in the next year or two. I'll keep you posted.

If you are a leader of your lake association or organization, you should receive a second email from me this afternoon with spreadsheets of data we collected from your lake(s).

Sincerely,

Tom

Swimmer's ItchGeneral Information Followed by the NEW Swimmer's Itch Partnership (see details below)Email Sandra Michalik if you have a suspected case of swimmer's itch!sandralmichalik@gmail.com

_What is
swimmer's itch? Swimmer's itch is a skin rash caused by a
parasite (shistosomes) which ordinarily infect birds, semi-aquatic mammals, and
snails. Common grackles, red-winged blackbirds, ducks, geese, swans, muskrats
and moles have been found to carry the parasite. As part of their developmental
life-cycle, these parasites are released from infected snails, migrate through
the water, and are capable of penetrating the skin of man. After penetration,
these parasites remain in the skin and die but can cause an allergic reaction
in some people. The parasite in man does not mature, reproduce or cause any
permanent infection.Who gets
swimmer's itch?Only about one third of the people who come in
contact with the parasite develop swimmer's itch. People who swim or wade in
infested water may experience this itchy rash. All age groups and both sexes
can be involved, but children are most often infected due to their habits of
swimming or wading in shallow water and playing on the beach as the water
evaporates from the skin. Swimmer's itch may be prevalent among bathers in
lakes in many parts of the world, including the Great Lakes region of North
America and certain coastal beaches.How is
swimmer's itch spread? An individual may get the infection by swimming
or wading in infested water and then allowing water to evaporate off the skin
rather than drying the skin with a towel. Person-to- person spread does not
occur.What are the
symptoms of swimmer's itch? Whenever infested water is allowed to evaporate
off the skin, an initial tingling sensation may be felt associated with the
penetration of the parasite into the skin. The irritated spot reaches its
maximum size after about 24 hours; the itching may continue for several days.
The symptoms should disappear within a week.How soon do
the symptoms begin? A person's first exposure to infested water may
not result in the itchy rash. Repeated exposure increases a person's allergic
sensitivity to the parasite and increases the likelihood of rash development.
Symptoms may appear within 1 to 2 hours of exposure.What is the
treatment for swimmer's itch? There is no treatment necessary
for swimmer’s itch. Some people may get relief from the itching by applying
skin lotions or creams to the infected site.When can you
get swimmer's itch? The first outbreaks usually occur in late May or
early June. The outbreaks in Wisconsin may last from 2 weeks in the northern
lakes to a month in the southern lakes. In some lakes it may last the entire
summer.

What can be done to reduce the chances of getting swimmer's itch?

Toweling off immediately after swimming or wading in infested water can be very helpful in preventing rash development.

Swim in water away from the shore.

Avoid swimming in areas where snails have accumulated.

Don't encourage birds to stay near swimming areas by feeding them.

Swimmer's Itch Partnership- A group of concerned property owners on Higgins Lake helped to form the partnership to investigate all aspects of swimmer's itch: prevalence, financial impacts, control methods. We are working with many groups to determine the prevalence on Lake Margrethe. If you or anyone visiting you gets a rash that you think is swimmer's itch please contact Sandra Michalik by email.... sandralmichalik@gmail.comTHANKS!